This invention relates to a crimp for an optical cable connector.
There are numerous designs of connectors for optical cables.
Many such designs were developed for use in indoor environments.
In the field of optical cable installations, however, there is a frequent need to connect cables in so-called “outside plant” (OSP) applications. Typically the cables, and the connectors secured thereto, used in OSP applications must withstand high pull forces caused by eg. environmental influences such as wind, snow and other forms of precipitation. Despite this requirement, for various reasons it is often impossible to avoid using the indoor connector designs in OSP applications.
One form of known indoor cable connector 10 is shown in FIG. 1.
The connector 10 includes a connector body 11 defining a hollow interior 12.
A dividing wall (not visible in FIG. 1) divides the hollow interior and provides support for a rearwardly extending, hollow, cylindrical, metal spigot 13. Spigot 13 extends rearwardly from the dividing wall to protrude via an aperture 14 formed in the end of the connector 10 visible in FIG. 1.
The opposite end 16 of the connector 10 includes connector parts intended for mating with other connector components for the purpose of making an optical fibre connection. The precise nature of these connector parts is variable according to the design of connector under consideration. Those skilled in the art will be familiar with the various known connector arrangements.
In order to secure an optical fibre cable 17 to the connector 10 it is necessary to remove a length of the cable jacket 18 from one end of the cable to expose the cable core assembly 19 and the reinforcing fibres 21, which latter typically are Kevlar fibres.
To secure the connector 10 and the cable 17 together it is necessary to insert the cable through a cylindrical, crushable, metal crimp 22 that as shown in FIG. 1 is a parallel-sided, circular hollow cylinder. Typically this step occurs before removal of the cable jacket as described above.
Thereafter the cable core assembly 19 is inserted into the spigot 13 so as to make an optically transmitting contact with the remainder of the operative components of the connector 10. The Kevlar fibres are then placed around the exterior of the spigot 13, and the crimp 22 advanced to trap the Kevlar fibres 21 between the interior of crimp 22 and the exterior of spigot 13.
A final step in the assembly of the connector 10 involves crushing the crimp 22 (eg. using a crimping tool) onto the exposed part of the spigot 13 and the cable jacket 18.
Following these assembly steps, the connector 10 may be inserted into eg. a socket of per se known design. The mating of the connector and socket typically will withstand a tensile load applied longitudinally to the cable 17 of about 40 N, before the connector 10 is pulled out of socket.
A connection of this strength is comfortably adequate when the connector 10 is used in indoor environments, but for the reasons stated hereinabove it is potentially inadequate when used in OSP applications.
A solution to this problem proposed in the prior art is to provide, between eg. the connector body 11 and a location on the cable jacket, a strain relieving line or structure. This provides a load transfer path for tensile loads that relieves strain on the connector 10. However, this arrangement is time-consuming to assemble. Consequently it is seriously disadvantageous, for example when an operator has to prepare many tens or hundreds of connectors for use in OSP applications.
Furthermore although it is commonplace for optical cables to be pre-terminated with connectors in a factory environment, sometimes it is necessary to assemble the connectors onto the cables in situ. In harsh or cold weather the need for this activity renders the use of additional, strain-relieving bridging components particularly inconvenient.